Distillation of tar or pitch to coke and apparatus therefor



S. P. MILLER April 18, 1933.

DISTILLATION OF TAR OR PITCH TO COKEAND APPARATUS THEREFOR Filed Aug. 9, 1929 3 Sheets-Sheet 1 INVENTOR ra a,

ATTORNEYS WWW April 18, 1933.

S. P. MILLER DISTILLATION OF TAR 0R PITCH TO COKE AND APPARATUS THEREFOR S Sheets-Sheet 2 Filed Aug. 9, 1929 lNvNT MM (bi/ 79 I 19 7 BY 77 i aw-J ATTORNEYS April 1933- I s. P. MILLER 1,904,504

DISTILLATION OF TAR OR PITCH TO COKE AND APPARATUS THEREFOR Filed Aug. 9, 1929' s Sheets-Sheet s k *2 Q & a Q c Q g m F a w m a W Qv v Q U Q INVENT R fig N ELM/M 1524M K E Q I ATTORNEYS Patented Apr. 18, 1933 UNITED STATES PATENT OFFICE STUART PARMELEE MILLER, OF ENGLEWOOD, NEW JERSEY, ASSIGNOB TO THE BARRETT COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY DISTILLATION OI TAB OB PITCH TO COKE AND APPARATUS THEREFOR Application filed August 9, 1929. Serial No. 384,667.

. This invention relates to improvements in the distillation of tar or pitch to coke in which the distillation is carried on continuously in a still heated externally while hot coal distillation gases are passed through the still to remove vapors from the distillation of the tar or pitch as they are formed;

According to the present invention, tar or pitch is distilled to coke by direct contact with a current of hot coal distillation ases, and the tar or pitch is also heated by in irect contact with highly heated gases to promote the coking operation. The vapors distilled during the coking operation are swept from the still by the hot coal distillation gases. The presence of the inert gases passing through the still lowers substantially the temperature at which the volatile components of the tar or pitch may be distilled, thus not only avoiding decomposition which would result at higher temperatures, but also increasing the relative rate of removal of the volatile components of the tar or pitch. This aids in the'conversion of the tar or pitch to coke, and increases by-product recovery, especially by the rapid removal of the high boilin constituents of the pitch. The hot coa -tillation gases enter the still at a temperature at which oils formed from the coal during 30 the distillation are still in vapor form. After leaving the still, these oils, together with constituents volatilized durin the coking o ration, are condensed from t e gases b coo g.

Hot coal distillation gases as t ey leave 35 the ovens or retorts carry with them fine 'particles of entrained impurities such as dust,

coke, pitch, etc. Such suspended particles as are carried through the coking still will, at least to some extent, be separated from the ases with the oils produced on cooling. Iowever, by subjecting the gases as they leave the coking still and while they are still at a high temperature to a cleaning operation, as by cleanin in an electrical precipitator or in a scrub r, the entrained impurities may be removed from the gases so that on subsequent cooling of the gases clean oils will be obtained.

In order to clean the gases, they ma be 50 scrubbed with tar or pitch which may a application of heat from outside of the still, t

pitch of the same composition as that carried in the gases. The scrubbing ma advantageously be accomplished by sub ecting the gases to an intense spray of the scrubbing medium. A preferred form of scrubber comprises a chamber in the bottom of which a small body of the scrubbing medium is maintained, 'and'in which a roll adapted to be rotated at high speed is positioned in such. a way that it dips but to a slight extent into the body of the scrubbing medium. The roll rotates in such a direction that it throws an intense spray of the scrubbing medium into the gases, scrubbing the gases and thoroughly washing the chamber walls to prevent the accumulation of deposits of pitch or coke thereon.

Where tar is to be distilled to coke, the tar or partially distilled tar may with'advantage be employed as the scrubbing medium for removing entrained impurities from the gases leaving the coking still, and the temperatures may be so adjusted that the tar is distilled by the hot gases leaving the still. The

partially distilled tar or pitch thus formed will be supplied to the coking still and the vapors and gases from the tar distillation will blend with the vapors and gases from the coking operation, and on subsequent cooling oils which will be clean oil and which will comprise constituents originally present in the tar and pitch and also oils originally present as vapors in the coal distillation gases, will be separated from the gases.

According to this invention, a body of pitch is maintained in a still and a thin layer of the pitch is formed on a moving surface and on exposure to thehot distillation ases passing through the still combined wit the e pitch is coked and the coke thus produced is continuously removed from the moving surface by a suitable scraping or disintegrating device. The moving surface is advantageousl in the form of a drum which di s into the dy of pitch maintained within tiie still. The drum is heated from the inside in any suitable manner, as by passing hot combustion gases throu h the drum. The rocess is continuous. Alt ough the gases rom a single coke oven or retort vary considerably in temperature and composition during the coking of a charge of coal, by blending the tion is illustrated more particularly as applied to use in connection with a coke oven battery, but it is intended and is to be understood that the invention is not limited thereto, but is applicable also to use in connection with other coal distillation plants.

Fig. 1 shows in plan a coke oven battery with a coking still and a tar still in series with the hot coke oven gases passing through the coking still and then through the tar still and the tar after distillation to pitch in the tar still assing to the coke still, countercurrent to the flow of the gases;

Fig. 2 is an elevation of the coking and tar stills;

Fig. 3 is a section through the coking still;

Fig. 4 is a section through the tar still;

Fig. 5 is a plan view of a modified arrangement in which the gases leaving the coking still are'cooled without first being cleaned;

ljlig. 6 is a section on the line 66 of Fig. 5; an I Fig. 7 is a section on the line 7 7 of Fig. 5.

In the drawings, 5 indicates acoke oven battery. The collector main 6 is connected with the individual ovens through uptake pipes 7. A cross over main 8 passes to condensers, etc. (not shown). This apparatus is of the usual type and is shown more or less diagrammatically. At the rear of the ovens is a coking still 9. Uptake pipes 10 from selectedovens pass directly into the coking still. By the proper manipulation of valves in the uptake pipes 10 and the uptake'p'i es 7, the gases from the selected ovens may directed either to the collector main 6 or to the coking still 9.

The still may be cylindrical in shape. Within the still is a drum 11 heated by hot gases such as hot combustion gases which .enter the drum at 12 and are drawn off from the drum at 13. The drum is slowly rotated, e. by meansof the gears 19 fromany suitab e source of power, and in rotating dips into a body of the pitch maintained within the still, and as this pitch is brought up into the atmosphere of the hot coal distillation gases as the drum rotates, the pitch, with the aid of heat supplied from an'external source to the interior of the drum, is coked. The hot coke oven gases passing through the still removevapors from almost as soon as t ey are formed andthus aid in the production of the coke. The rotation of the drum is so timed that the pitch is coked on the drum before being removed.

When the drum rotates to the position where ing proximity with the pitch it contacts with the scraper-'13' coke is re;

moved by the scraper and discl1arges;.-into the chute v14. -A rotating gratef lo c ontrols therate at which coke is discharged" froni the; i

The hot coal distillation gase's .leavilig'the -;z,

still contain vapors originally-present in the gases as they leave the ovens fand-Ein addition vapors resulting from the vaporization and decomposition of the pitch within'the coking still 9. These hot gasesand- Vapors pass through the main 20 to the tarscrubber and still 21. I

Tar is admitted to the still through the pipe 22. This tar is advantageously heated before entering the still. It may be preheated by indirect contact with the hot gases and vapors leaving the still, whereby oils will be condensed from the gases simultaneously with the heating of the tar. A body of tar or partially distilled tar is maintained in the bottom of this still. The still is equipped with a spray device for producing within the still an intense spray of the tarry material which scrubs the gases and cleans them,

and at the same time effects distillation of the tarry material by contact with the hot gases.

uenl'clhed called tar-fog, etc., from the gases'so that the gases leaving the still through the settling tower 25 are free from entrained impurities with the exception of possible-particles of the spray carried over "from th e'; still by the gases. I of pitch spray from the gases,-th'e freshtar is advantageously fed' to the still, througli' the tower 25 and the tower is equippedf'with baffles 26 over which the tar flows, whereby any entrained drops of tar are washed from the gases and the .tar is partially distilled.

The gases pass out of the tower into condensing means 26 which may becondensers of the direct or indirect type. Direct con- 11 order to remove such droplets densers are here shown with means for spray-.

Th ihe gases with water or ammonia liquor.

ondensate, together with the excess coolcollected in the receivers28. Beyond the condensers is an exhauster 29 which" is provided for drawingthe gases and vapors through the-system. Means for the recovcry'of ammonia, light oils, etc; is provided beyond the P125 exhauster.

The tar is distilled in the still to produce edium, is collected in the decanters 27. Fro the decanters the clean oil is separately I and leveling arm 31 and supplied through the line 32 to the still 9. The depth of tar in the still 21 is controlled by the postion of the leveling arm 31, and the depth of tar in this still determines the nature of the spray thrown from the roll 23. Within-the still 9 the pitch is further distilled and coked and the coke produced is continuously discharged through the chute 14.

Fig. 5 shows a modified arrangement in which the gases from selected ovens are passed up through the uptake pipes 55 and are collected in the hot gas header 56 and passed through the still 60 which is of the same general type as that described; however,

in the still here shown, the coke oven gasespass through the still from one end to the other. The gases and vapors leaving the still are cooled without cleanin and tarry oils separate from the gases. hese tarry oils comprise oils originally present in the gases enterin the still and oils volatilized within the stil and in addition comprise entrained impurities carried from the ovens by' the gases and removed from the gases during the separation of the oils.

The hot cokeoven gases enter the still 60 through the main 61, and in passing through the still sweep out the vapors formed and aid in the distillation of the pitch. The pitch is fed to the still through the trough 62 and the seal 63. A body of pitch is maintained in the still, and the drum 65, heated internally by hot gases which enter at 68 and leave at 69, revolves slowly in this body of pitch, and as it revolves exposes a thin layer of the pitch to the action of the hot coke oven gases passing through thestill.

Pitch which adheres to the drum as it revolves is distilled and coked by the combined action of the hot gases which ass throu h the drum in indirect contact wit the pitc and give up sensible heat to the pitch, and of the hot coal distillation gases which sweep through the still, removing vapors as the are formed, and increasing the rate at whic the volatile consituents of the pitch volatilize. The drum 65 is revolved at such a rate that the pitch is coked before it reaches the scraper 7 0. The coke removed from the drum collects in the chute 71 and is slowly discharged through the revolving grate 72 into the tank.

of water 73. The finished coke may be re moved from the tank by any suitable means, as, for example, the continuous belt 74. This belt is advantageously sopositioned that the coke remains in the water in the tank 73 a sufliciently long time to become thoroughly quenched, but yet is removed before it becomes water soaked.

The hot gases in assing through the still remove the vapors rom proximity with the pitch almost immediately as they are formed. This not only hastens the distillation of volatile constituents from the pitch but likewise high boiling resinous distillate.

and the gases and. vapors are free from de- I composition products which would result if the vapors were maintained at a high temperature over a prolonged period of time. Pitch or partially distilled tar may be distilled in this still. Tar is advantageously partially distilled in other apparatus especially designed for the distillation of thinly fluid tar before being admitted to the still. This may be a still in which the tar is brought into intimate contact with hot coal distillation gases in the form of a fine spray, such as that disclosed in Fig. 1.

The hot enriched gases leaving the still 60 are not clean gases", but may contain particles of pitch, coke, etc., together with the usual tar fog, which were present in the gases as they left the ovens, and which will separate with the oils on cooling to give tarry oils and The gases comprise constituents of high boilin range, viz. resins and greases distilled from t e pitch in converting it to coke. These high boiling constituents are advantageously separated from the gases in a special hot condenser 75, which ma advantageously be an indirect cons denser. y passing the gases up through this condenser, semi-solid resinous constituents of high boiling range which separate from the gases in the bottom of the condenser, will be washed down with oils of lower boiling range which will separate in the top of this condenser, and the cooling is preferably so regulated that a suflicient quantity of oils of lower boilin range is separated in the upper portion 0 the condenser to prevent the condenser becoming choked up with the resinous, semisolid condensate. This high boiling fraction is separately collected in the tank 76.

The ases pass from the hot condenser to the condensers 77 in which separate tarry oil fractions may be obtained or one total tarry oil may be produced. B spraying the 'gases with water and cooling t em to the ordinary temperature, both heavy and lighter oils may be condensed from the gases and collected in the decanters 7 8, From the decanters the oil may be readil obtained. An exhauster 79 is shown for rawing the gases through the still and condensers, etc.

Instead of passing thegases directly from the still to the condensers, the gases may first.

gases through one still and then through a second still, adding tar to the second still, spraying it in the form of an intense spray into direct and intimate contact with the hot gases in the second still, whereby the gases are cleaned and the tar is distilled, drawing off the residue resulting from this distillation of the tar and adding it to the first still, exposing a film of this distilled tar to the action of the hot coal distillation gases within this first still while simultaneously applying additional heat to the film, whereby the film of partly distilled tar is converted to coke, discharging the coke from the first still, collecting the hot clean enriched gases leaving the second still and cooling them to separate oils therefrom. r

2. In combination with coal distillation apparatus, a cokingst-ill, means for passing hot coal distillation gases from the coal distillation' apparatus to the coking still, a tar still, means for passing the gases and vapors from the coking still into the tar still, means for producing an intense spray of tar in the tar still, coolers for condensing oils from the gases and'vapors, means for conveying gases and vapors from the coking still to the coolers, a pitch outlet from the tar still to the coking still, a drum positioned in the coking still on a horizontal axis with means for revolving it at a slow rate of speed, the drum being so situated as to dip into a reservoir for pitch in the still, means for heating the drum internally, a chute for discharging coke from the still and a scraper for removing cokefrom the drum and adapted to discharge 7 the coke from the still through the chute.

In testimony whereof'I afiix my signature.

STUART PARMELEE MILLER. 

